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WO2021054372A1 - Dispositif d'inspection et procédé d'inspection - Google Patents

Dispositif d'inspection et procédé d'inspection Download PDF

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Publication number
WO2021054372A1
WO2021054372A1 PCT/JP2020/035120 JP2020035120W WO2021054372A1 WO 2021054372 A1 WO2021054372 A1 WO 2021054372A1 JP 2020035120 W JP2020035120 W JP 2020035120W WO 2021054372 A1 WO2021054372 A1 WO 2021054372A1
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WO
WIPO (PCT)
Prior art keywords
crack
modified region
semiconductor substrate
tip
wafer
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2020/035120
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English (en)
Japanese (ja)
Inventor
いく 佐野
剛志 坂本
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Hamamatsu Photonics KK
Original Assignee
Hamamatsu Photonics KK
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hamamatsu Photonics KK filed Critical Hamamatsu Photonics KK
Priority to KR1020227004588A priority Critical patent/KR102816180B1/ko
Priority to CN202080065240.3A priority patent/CN114430706B/zh
Priority to DE112020004475.0T priority patent/DE112020004475T5/de
Priority to US17/642,998 priority patent/US20220331909A1/en
Publication of WO2021054372A1 publication Critical patent/WO2021054372A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/36—Removing material
    • B23K26/40—Removing material taking account of the properties of the material involved
    • B23K26/402—Removing material taking account of the properties of the material involved involving non-metallic material, e.g. isolators
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/70—Manufacture or treatment of devices consisting of a plurality of solid state components formed in or on a common substrate or of parts thereof; Manufacture of integrated circuit devices or of parts thereof
    • H01L21/77—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate
    • H01L21/78—Manufacture or treatment of devices consisting of a plurality of solid state components or integrated circuits formed in, or on, a common substrate with subsequent division of the substrate into plural individual devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/50—Working by transmitting the laser beam through or within the workpiece
    • B23K26/53—Working by transmitting the laser beam through or within the workpiece for modifying or reforming the material inside the workpiece, e.g. for producing break initiation cracks
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/03—Observing, e.g. monitoring, the workpiece
    • B23K26/032—Observing, e.g. monitoring, the workpiece using optical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K37/00—Auxiliary devices or processes, not specially adapted for a procedure covered by only one of the other main groups of this subclass
    • B23K37/04—Auxiliary devices or processes, not specially adapted for a procedure covered by only one of the other main groups of this subclass for holding or positioning work
    • B23K37/0408—Auxiliary devices or processes, not specially adapted for a procedure covered by only one of the other main groups of this subclass for holding or positioning work for planar work
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
    • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
    • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
    • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
    • H01L21/322—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to modify their internal properties, e.g. to produce internal imperfections
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2101/00—Articles made by soldering, welding or cutting
    • B23K2101/36—Electric or electronic devices
    • B23K2101/40—Semiconductor devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K2103/00—Materials to be soldered, welded or cut
    • B23K2103/50—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26
    • B23K2103/56—Inorganic material, e.g. metals, not provided for in B23K2103/02 – B23K2103/26 semiconducting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/02—Positioning or observing the workpiece, e.g. with respect to the point of impact; Aligning, aiming or focusing the laser beam
    • B23K26/06—Shaping the laser beam, e.g. by masks or multi-focusing
    • B23K26/062—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam
    • B23K26/0622—Shaping the laser beam, e.g. by masks or multi-focusing by direct control of the laser beam by shaping pulses
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K31/00—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups
    • B23K31/12—Processes relevant to this subclass, specially adapted for particular articles or purposes, but not covered by only one of the preceding main groups relating to investigating the properties, e.g. the weldability, of materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/67005—Apparatus not specifically provided for elsewhere
    • H01L21/67011—Apparatus for manufacture or treatment
    • H01L21/67092—Apparatus for mechanical treatment

Definitions

  • One aspect of the present invention relates to an inspection device and an inspection method.
  • the wafer By irradiating the wafer with laser light from the back surface side of the semiconductor substrate in order to cut the wafer including the semiconductor substrate and the functional element layer formed on the surface of the semiconductor substrate along each of the plurality of lines, the wafer is irradiated with laser light.
  • a laser processing device that forms a plurality of rows of modified regions inside a semiconductor substrate along each of a plurality of lines is known.
  • the laser processing apparatus described in Patent Document 1 includes an infrared camera, and observes a modified region formed inside the semiconductor substrate, processing damage formed on the functional element layer, and the like from the back surface side of the semiconductor substrate. Is possible.
  • the wafer may be irradiated with laser light from the back surface side of the semiconductor substrate under the condition that cracks are formed over a plurality of rows of modified regions.
  • a plurality of wafers may be provided in a later process. It may not be possible to reliably cut along each of the lines.
  • One aspect of the present invention is to provide an inspection device and an inspection method capable of confirming whether or not a crack extending over a modified region sufficiently extends to the surface side of a semiconductor substrate.
  • the inspection apparatus has a stage that supports a wafer having a semiconductor substrate having a first surface and a second surface, a laser irradiation unit that irradiates the wafer with laser light, and transparency to the semiconductor substrate.
  • the image pickup unit that outputs the light having the above and detects the light propagating on the semiconductor substrate, and the laser irradiation so that one or more modified regions are formed inside the semiconductor substrate by irradiating the wafer with the laser beam.
  • the position of the tip of the upper crack on the second surface side which is a crack extending from the modified region to the second surface side of the semiconductor substrate, is derived by controlling the unit.
  • the control unit comprises a control unit configured to execute, and the control unit has a modification region along each of the plurality of lines in the wafer, which has a different formation depth from the other lines contained in the plurality of lines.
  • the laser irradiation part is controlled so as to be formed, and the tip of the tip on the second surface side of the upper crack is formed in order from the line where the formation depth of the modified region is shallow or from the line where the formation depth of the modified region is deep.
  • the difference between the position and the position where the modified region is formed is derived, and it is determined whether or not the crack is reached based on the amount of change in the difference.
  • the wafer is irradiated with laser light so that a modified region is formed inside the semiconductor substrate, and the transmissive light propagating through the semiconductor substrate is imaged, and the imaging result (output from the imaging unit) is captured.
  • the position of the tip of the upper crack on the second surface side which is a crack extending from the modified region to the second surface side of the semiconductor substrate, is derived.
  • the modified regions of each of the plurality of lines have different formation depths, and the formed depths of the modified regions are in order from the shallowest line or the formed depth of the modified region.
  • the difference between the position of the tip of the upper crack and the position where the modified region is formed is derived in order from the deep line, and it is determined whether or not the crack is reached based on the amount of change in the difference.
  • the present inventors are in a crack arrival state and a state in which the crack does not reach the first surface side of the semiconductor substrate.
  • the amount of change in the above-mentioned difference (the amount of change from the line from which the difference was derived immediately before) is larger than that between other lines in the line where and is switched. From this point of view, in this inspection device, it is determined whether or not the crack has reached a state based on the amount of change in the difference described above. From this, according to this inspection apparatus, it is properly confirmed whether or not the crack has reached, that is, whether or not the crack over the modified region is sufficiently extended to the first surface side of the semiconductor substrate. Can be done.
  • the inspection apparatus has a stage that supports a wafer having a semiconductor substrate having a first surface and a second surface, a laser irradiation unit that irradiates the wafer with laser light, and transparency to the semiconductor substrate.
  • An imaging unit that outputs light having the above and detects light propagating through the semiconductor substrate, and a laser so that one or more modified regions are formed inside the semiconductor substrate by irradiating the wafer with the laser beam. Based on the control of the irradiation unit and the signal output from the imaging unit that detects light, the position of the tip of the upper crack on the second surface side, which is a crack extending from the modified region to the second surface side of the semiconductor substrate, is determined.
  • a modification region comprising, and a control unit configured to perform, along each of the plurality of lines in the wafer, having a different formation depth from the other lines contained in the plurality of lines.
  • the laser irradiation part is controlled so that the formed region is formed, and the tip on the second surface side of the upper crack is formed in order from the line where the formation depth of the modified region is shallow or from the line where the formation depth of the modified region is deep. Is derived, and based on the amount of change in the position of the tip, it is determined whether or not the crack has reached.
  • the wafer is irradiated with laser light so that a modified region is formed inside the semiconductor substrate, and the transmissive light propagating through the semiconductor substrate is imaged, and the imaging result (output from the imaging unit) is captured.
  • the position of the tip of the upper crack on the second surface side which is a crack extending from the modified region to the second surface side of the semiconductor substrate, is derived.
  • the modified regions of each of the plurality of lines have different formation depths, and the formed depths of the modified regions are in order from the shallowest line or the formed depth of the modified region.
  • the position of the tip of the upper crack is derived in order from the deep line, and it is determined whether or not the crack has reached the state based on the amount of change in the position of the tip.
  • the crack arrival state and the crack are on the first surface side of the semiconductor substrate.
  • the amount of change in the position of the tip of the upper crack described above becomes larger than that between other lines. I found that. From this point of view, in this inspection device, it is determined whether or not the crack has reached the state based on the amount of change in the position of the tip of the upper crack described above. From this, according to this inspection apparatus, it is properly confirmed whether or not the crack has reached, that is, whether or not the crack over the modified region is sufficiently extended to the first surface side of the semiconductor substrate. Can be done.
  • the control unit determines whether or not the crack has reached, the presence or absence of the tip on the first surface side of the lower crack, which is a crack extending from the modified region to the first surface side of the semiconductor substrate, is also taken into consideration. Good. If the presence of the tip on the first surface side of the lower crack is confirmed, it is assumed that the crack has not reached the state. Therefore, by determining whether or not the crack has reached the state based on the presence or absence of the tip on the first surface side of the lower crack, it is possible to determine with high accuracy whether or not the crack has reached the state.
  • the control unit may further execute to derive information related to the adjustment of the irradiation conditions of the laser irradiation unit based on the determination result of whether or not the crack has reached.
  • information related to the adjustment of the irradiation conditions of the laser irradiation unit in consideration of the judgment result, for example, when the crack length is shorter than the original length, the crack length is increased.
  • Information for adjusting the irradiation conditions can be derived so that the length of the crack becomes shorter when the length of the crack is longer than the original length. Then, by adjusting the irradiation conditions using the information for adjusting the irradiation conditions derived in this way, the length of the crack can be set to a desired length. As described above, according to this inspection device, the length of the crack over the modified region can be set to a desired length.
  • the control unit may estimate the crack length based on the determination result and derive information related to the adjustment of the irradiation condition based on the estimated crack length. By deriving the information related to the adjustment of the irradiation conditions based on the estimated crack length, the adjustment accuracy of the irradiation conditions can be improved, and the crack length can be set to the desired length with higher accuracy.
  • a wafer having a semiconductor substrate having a first surface and a second surface is prepared, and the wafer is irradiated with laser light to modify one or more inside the semiconductor substrate.
  • the position of the tip of the upper crack on the second surface side which is a crack extending from the modified region to the second surface side of the semiconductor substrate, is derived, and the tip of the upper crack on the second surface side is derived.
  • the first step includes a third step of determining whether or not the crack extending from the modified region has reached the first surface side of the semiconductor substrate based on the position of the wafer.
  • a modified region having a different formation depth from the other lines contained in the plurality of lines is formed, and in the third step, the modified region is formed in order from the shallowest line.
  • the difference between the position of the tip on the second surface side of the upper crack and the position where the modified region is formed is derived in order from the line where the formation depth of the modified region is deep, and based on the amount of change in the difference. , Determine whether or not the crack has reached.
  • a wafer having a semiconductor substrate having a first surface and a second surface is prepared, and the wafer is irradiated with laser light to modify one or more inside the semiconductor substrate.
  • the position of the tip of the upper crack on the second surface side which is a crack extending from the modified region to the second surface side of the semiconductor substrate, is derived, and the tip of the upper crack on the second surface side is derived.
  • the first step includes a third step of determining whether or not the crack extending from the modified region has reached the first surface side of the semiconductor substrate based on the position of the wafer.
  • a modified region having a different formation depth from the other lines contained in the plurality of lines is formed, and in the third step, the modified region is formed in order from the shallowest line.
  • the position of the tip on the second surface side of the upper crack is derived in order from the line where the formation depth of the modified region is deep, and whether or not the crack has reached is determined based on the amount of change in the position of the tip. judge.
  • an inspection device and an inspection method capable of confirming whether or not a crack extending over a modified region sufficiently extends to the first surface side of the semiconductor substrate.
  • FIG. 5 is a cross-sectional view of a wafer for explaining the imaging principle by the inspection imaging unit shown in FIG. 5, and images at each location by the inspection imaging unit.
  • FIG. 5 is a cross-sectional view of a wafer for explaining the imaging principle by the inspection imaging unit shown in FIG. 5, and images at each location by the inspection imaging unit.
  • FIG. 5 is an optical path diagram for explaining the imaging principle by the inspection imaging unit shown in FIG. 5, and a schematic view showing an image at a focal point by the inspection imaging unit.
  • FIG. 5 is an optical path diagram for explaining the imaging principle by the inspection imaging unit shown in FIG. 5, and a schematic view showing an image at a focal point by the inspection imaging unit.
  • It is a schematic diagram which shows the formation image of the modified region for inspection.
  • It is a schematic diagram which shows the acquisition image of a plurality of images by moving a focal point F. It is a table which shows an example of the imaging result at each measurement point.
  • the laser processing apparatus 1 (inspection apparatus) includes a stage 2, a laser irradiation unit 3, a plurality of imaging units 4, 5 and 6, a drive unit 7, and a control unit 8. I have.
  • the laser processing device 1 is a device that forms a modified region 12 on the object 11 by irradiating the object 11 with the laser beam L.
  • Stage 2 supports the object 11 by, for example, adsorbing a film attached to the object 11.
  • the stage 2 can move along the X direction and the Y direction, respectively, and can rotate around an axis parallel to the Z direction as a center line.
  • the X direction and the Y direction are the first horizontal direction and the second horizontal direction that are perpendicular to each other, and the Z direction is the vertical direction.
  • the laser irradiation unit 3 collects the laser beam L having transparency to the object 11 and irradiates the object 11.
  • the laser light L is particularly absorbed at the portion corresponding to the focusing point C of the laser light L, and the laser light L is modified into the inside of the object 11.
  • the quality region 12 is formed.
  • the modified region 12 is a region whose density, refractive index, mechanical strength, and other physical properties are different from those of the surrounding non-modified region.
  • the modified region 12 includes, for example, a melt processing region, a crack region, a dielectric breakdown region, a refractive index change region, and the like.
  • the modified region 12 has a characteristic that cracks easily extend from the modified region 12 to the incident side of the laser beam L and the opposite side thereof. Such characteristics of the modified region 12 are utilized for cutting the object 11.
  • a plurality of modified spots 12s are 1 along the X direction. Formed to line up.
  • One modified spot 12s is formed by irradiation with one pulse of laser light L.
  • the modified region 12 in one row is a set of a plurality of modified spots 12s arranged in one row. Adjacent modified spots 12s may be connected to each other or separated from each other depending on the relative moving speed of the focusing point C with respect to the object 11 and the repetition frequency of the laser beam L.
  • the imaging unit 4 images the modified region 12 formed on the object 11 and the tip of the crack extending from the modified region 12.
  • the image pickup unit 5 and the image pickup unit 6 take an image of the object 11 supported by the stage 2 with the light transmitted through the object 11.
  • the images obtained by the imaging units 5 and 6 are, for example, used for alignment of the irradiation position of the laser beam L.
  • the drive unit 7 supports the laser irradiation unit 3 and a plurality of imaging units 4, 5 and 6.
  • the drive unit 7 moves the laser irradiation unit 3 and the plurality of imaging units 4, 5 and 6 along the Z direction.
  • the control unit 8 controls the operations of the stage 2, the laser irradiation unit 3, the plurality of imaging units 4, 5 and 6, and the drive unit 7.
  • the control unit 8 is configured as a computer device including a processor, a memory, a storage, a communication device, and the like.
  • the processor executes software (program) read into the memory or the like, and controls reading and writing of data in the memory and storage, and communication by the communication device.
  • the object 11 of this embodiment is a wafer 20 as shown in FIGS. 2 and 3.
  • the wafer 20 includes a semiconductor substrate 21 and a functional element layer 22.
  • the wafer 20 is described as having the functional element layer 22, but the wafer 20 may or may not have the functional element layer 22, and may be a bare wafer.
  • the semiconductor substrate 21 has a front surface 21a (first surface, laser irradiation back surface) and a back surface 21b (second surface, laser irradiation surface).
  • the semiconductor substrate 21 is, for example, a silicon substrate.
  • the functional element layer 22 is formed on the surface 21a of the semiconductor substrate 21.
  • the functional element layer 22 includes a plurality of functional elements 22a arranged two-dimensionally along the surface 21a.
  • the functional element 22a is, for example, a light receiving element such as a photodiode, a light emitting element such as a laser diode, a circuit element such as a memory, or the like.
  • the functional element 22a may be configured three-dimensionally by stacking a plurality of layers.
  • the semiconductor substrate 21 is provided with a notch 21c indicating the crystal orientation, an orientation flat may be provided instead of the notch 21c.
  • the wafer 20 is cut along each of the plurality of lines 15 for each functional element 22a.
  • the plurality of lines 15 pass between the plurality of functional elements 22a when viewed from the thickness direction of the wafer 20. More specifically, the line 15 passes through the center of the street region 23 (center in the width direction) when viewed from the thickness direction of the wafer 20.
  • the street region 23 extends so as to pass between adjacent functional elements 22a in the functional element layer 22.
  • the plurality of functional elements 22a are arranged in a matrix along the surface 21a, and the plurality of lines 15 are set in a grid pattern.
  • the line 15 is a virtual line, it may be a line actually drawn.
  • the laser irradiation unit 3 includes a light source 31, a spatial light modulator 32, and a condenser lens 33.
  • the light source 31 outputs the laser beam L by, for example, a pulse oscillation method.
  • the spatial light modulator 32 modulates the laser beam L output from the light source 31.
  • the spatial light modulator 32 is, for example, a spatial light modulator (SLM) of a reflective liquid crystal (LCOS: Liquid Crystal on Silicon).
  • SLM spatial light modulator
  • LCOS Liquid Crystal on Silicon
  • the laser irradiation unit 3 irradiates the wafer 20 with the laser beam L from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15 to form a semiconductor along each of the plurality of lines 15.
  • Two rows of modified regions 12a and 12b are formed inside the substrate 21.
  • the modified region (first modified region) 12a is the modified region closest to the surface 21a of the two rows of modified regions 12a and 12b.
  • the modified region (second modified region) 12b is the modified region closest to the modified region 12a among the modified regions 12a and 12b in the two rows, and is the modified region closest to the back surface 21b.
  • the two rows of modified regions 12a and 12b are adjacent to each other in the thickness direction (Z direction) of the wafer 20.
  • the two rows of modified regions 12a and 12b are formed by moving the two focusing points C1 and C2 relative to the semiconductor substrate 21 along the line 15.
  • the laser light L is modulated by the spatial light modulator 32 so that, for example, the focusing point C2 is located on the rear side in the traveling direction and on the incident side of the laser light L with respect to the focusing point C1.
  • the focusing point C2 is located on the rear side in the traveling direction and on the incident side of the laser light L with respect to the focusing point C1.
  • it may be single focus or multifocal, and may be one pass or multiple passes.
  • the wafer 20 is formed from the back surface 21b side of the semiconductor substrate 21 along each of the plurality of lines 15 under the condition that the cracks 14 extending over the modified regions 12a and 12b of the two rows reach the front surface 21a of the semiconductor substrate 21. Is irradiated with the laser beam L.
  • a semiconductor substrate 21 which is a single crystal silicon substrate having a thickness of 775 ⁇ m
  • two focusing points C1 and C2 are aligned at positions 54 ⁇ m and 128 ⁇ m from the surface 21a, and each of a plurality of lines 15 is formed.
  • the wafer 20 is irradiated with the laser beam L from the back surface 21b side of the semiconductor substrate 21.
  • the wavelength of the laser beam L is 1099 nm
  • the pulse width is 700 nsec
  • the repetition frequency is 120 kHz.
  • the output of the laser beam L at the condensing point C1 is 2.7 W
  • the output of the laser light L at the condensing point C2 is 2.7 W, which are relative to the two condensing points C1 and C2 with respect to the semiconductor substrate 21.
  • the moving speed is 800 mm / sec.
  • the formation of the two rows of modified regions 12a and 12b and the crack 14 is carried out in the following cases. That is, in a later step, the semiconductor substrate 21 is thinned by grinding the back surface 21b of the semiconductor substrate 21, cracks 14 are exposed on the back surface 21b, and the wafer 20 is formed on a plurality of semiconductors along each of the plurality of lines 15. When disconnecting to the device.
  • the image pickup unit 4 includes a light source 41, a mirror 42, an objective lens 43, and a light detection unit 44.
  • the light source 41 outputs light I1 having transparency to the semiconductor substrate 21.
  • the light source 41 is composed of, for example, a halogen lamp and a filter, and outputs light I1 in the near infrared region.
  • the light I1 output from the light source 41 is reflected by the mirror 42, passes through the objective lens 43, and irradiates the wafer 20 from the back surface 21b side of the semiconductor substrate 21.
  • the stage 2 supports the wafer 20 in which the two rows of modified regions 12a and 12b are formed as described above.
  • the objective lens 43 passes the light I1 reflected by the surface 21a of the semiconductor substrate 21. That is, the objective lens 43 passes the light I1 propagating through the semiconductor substrate 21.
  • the numerical aperture (NA) of the objective lens 43 is 0.45 or more.
  • the objective lens 43 has a correction ring 43a.
  • the correction ring 43a corrects the aberration generated in the optical I1 in the semiconductor substrate 21 by adjusting the distance between the plurality of lenses constituting the objective lens 43, for example.
  • the light detection unit 44 detects the light I1 that has passed through the objective lens 43 and the mirror 42.
  • the photodetector 44 is composed of, for example, an InGaAs camera, and detects light I1 in the near infrared region.
  • the imaging unit 4 can image the respective tips of the two rows of modified regions 12a and 12b and the plurality of cracks 14a, 14b, 14c and 14d (details will be described later).
  • the crack 14a is a crack extending from the modified region 12a toward the surface 21a.
  • the crack 14b is a crack extending from the modified region 12a to the back surface 21b side.
  • the crack 14c is a crack extending from the modified region 12b toward the surface 21a.
  • the crack 14d is a crack extending from the modified region 12b to the back surface 21b side.
  • the control unit 8 irradiates the laser irradiation unit 3 with the laser beam L under the condition that the cracks 14 extending over the modified regions 12a and 12b in the two rows reach the surface 21a of the semiconductor substrate 21 (see FIG. 4), but some trouble occurs. If the crack 14 does not reach the surface 21a due to the above, a plurality of such cracks 14a, 14b, 14c, 14d are formed.
  • the length of the crack is set in order to deal with the above-mentioned problems. Inspect and adjust the length of the crack according to the inspection result.
  • a modified region for inspection is formed on the wafer 20
  • the length of the crack extending from the modified region is determined, and the length of the crack is determined according to the length of the crack. Perform the adjustment process (details will be described later).
  • the image pickup unit 5 includes a light source 51, a mirror 52, a lens 53, and a light detection unit 54.
  • the light source 51 outputs light I2 having transparency to the semiconductor substrate 21.
  • the light source 51 is composed of, for example, a halogen lamp and a filter, and outputs light I2 in the near infrared region.
  • the light source 51 may be shared with the light source 41 of the image pickup unit 4.
  • the light I2 output from the light source 51 is reflected by the mirror 52, passes through the lens 53, and irradiates the wafer 20 from the back surface 21b side of the semiconductor substrate 21.
  • the lens 53 allows light I2 reflected on the surface 21a of the semiconductor substrate 21 to pass through. That is, the lens 53 passes the light I2 propagating through the semiconductor substrate 21.
  • the numerical aperture of the lens 53 is 0.3 or less. That is, the numerical aperture of the objective lens 43 of the image pickup unit 4 is larger than the numerical aperture of the lens 53.
  • the light detection unit 54 detects the light I2 that has passed through the lens 53 and the mirror 52.
  • the photodetector 55 is composed of, for example, an InGaAs camera, and detects light I2 in the near infrared region.
  • the imaging unit 5 irradiates the wafer 20 with light I2 from the back surface 21b side and detects the light I2 returning from the front surface 21a (functional element layer 22) to detect the functional element layer. 22 is imaged.
  • the image pickup unit 5 irradiates the wafer 20 with light I2 from the back surface 21b side and returns light from the formation positions of the modified regions 12a and 12b on the semiconductor substrate 21. By detecting I2, an image of a region including the modified regions 12a and 12b is acquired. These images are used for alignment of the irradiation position of the laser beam L.
  • the image pickup unit 6 has the same configuration as the image pickup unit 5 except that the lens 53 has a lower magnification (for example, 6 times in the image pickup unit 5 and 1.5 times in the image pickup unit 6). , Used for alignment in the same manner as the image pickup unit 5.
  • Imaging principle by inspection imaging unit Using the imaging unit 4 shown in FIG. 5, as shown in FIG. 7, with respect to the semiconductor substrate 21 in which the cracks 14 extending over the modified regions 12a and 12b in the two rows reach the front surface 21a, the front surface is from the back surface 21b side.
  • the focal point F focus of the objective lens 43
  • the focus F is focused on the tip 14e of the crack 14 extending from the modified region 12b to the back surface 21b side from the back surface 21b side, the tip 14e can be confirmed (the image on the right side in FIG. 7).
  • the focus F is focused on the crack 14 itself and the tip 14e of the crack 14 reaching the front surface 21a from the back surface 21b side, they cannot be confirmed (the image on the left side in FIG. 7).
  • the focus F is focused on the front surface 21a of the semiconductor substrate 21 from the back surface 21b side, the functional element layer 22 can be confirmed.
  • the back surface 21b side with respect to the semiconductor substrate 21 in which the cracks 14 extending over the modified regions 12a and 12b in the two rows do not reach the front surface 21a.
  • the focal point F is moved from the surface to the surface 21a side. In this case, even if the focus F is focused on the tip 14e of the crack 14 extending from the modified region 12a to the front surface 21a side from the back surface 21b side, the tip 14e cannot be confirmed (the image on the left side in FIG. 8).
  • the focal point F is aligned from the back surface 21b side with respect to the region opposite to the back surface 21b with respect to the front surface 21a (that is, the region on the functional element layer 22 side with respect to the front surface 21a), and is symmetrical with respect to the focal point F with respect to the front surface 21a.
  • the virtual focus Fv is positioned at the tip 14e, the tip 14e can be confirmed (the image on the right side in FIG. 8).
  • the virtual focal point Fv is a point symmetrical with respect to the focal point F in consideration of the refractive index of the semiconductor substrate 21 and the surface 21a.
  • 9 and 10 are SEM (Scanning Electron Microscope) images of the modified region 12 and the crack 14 formed inside the semiconductor substrate 21 which is a silicon substrate.
  • 9 (b) is an enlarged image of the region A1 shown in FIG. 9 (a)
  • FIG. 10 (a) is an enlarged image of the region A2 shown in FIG. 9 (b)
  • FIG. b) is a magnified image of the region A3 shown in FIG. 10 (a).
  • the width of the crack 14 is about 120 nm, which is smaller than the wavelength of light I1 in the near infrared region (for example, 1.1 to 1.2 ⁇ m).
  • the imaging principle assumed is as follows.
  • FIG. 11A when the focal point F is positioned in the air, the light I1 does not return, so that a blackish image is obtained (the image on the right side in FIG. 11A).
  • FIG. 11B when the focal point F is positioned inside the semiconductor substrate 21, the light I1 reflected by the surface 21a is returned, so that a whitish image can be obtained (FIG. 11B). ) On the right side).
  • FIG. 11 (c) when the focus F is focused on the modified region 12 from the back surface 21b side, the modified region 12 absorbs a part of the light I1 reflected and returned by the surface 21a. Since scattering or the like occurs, an image in which the modified region 12 appears blackish in a whitish background can be obtained (the image on the right side in FIG. 11C).
  • the focal point F when the focal point F is focused on the tip 14e of the crack 14 from the back surface 21b side, for example, the optical specificity (stress concentration, strain, etc.) generated in the vicinity of the tip 14e. (Discontinuity of atomic density, etc.), confinement of light generated near the tip 14e, etc. causes scattering, reflection, interference, absorption, etc. of a part of the light I1 reflected and returned on the surface 21a, resulting in a whitish background. An image in which the tip 14e appears blackish can be obtained (the image on the right side in (a) and (b) of FIG. 12). As shown in FIG.
  • the control unit 8 controls (forms) the laser irradiation unit 3 so that the wafer 20 is irradiated with the laser beam L to form one or more modified regions 12 for inspection inside the semiconductor substrate 21. Processing) and the crack arrival state in which the crack 14 extending from the modified region 12 reaches the surface 21a side of the semiconductor substrate 21 based on the image acquired by the image pickup unit 4 (the signal output from the image pickup unit 4).
  • It is configured to execute the determination of whether or not the laser irradiation unit 3 (determination process) and the derivation of information related to the adjustment of the irradiation conditions of the laser irradiation unit 3 based on the determination result (adjustment process). There is.
  • the control unit 8 controls the laser irradiation unit 3 so that the modified region 12 is formed along each of the plurality of lines on the wafer 20.
  • FIG. 13 shows a plurality of lines extending in the X direction and adjacent to each other in the Y direction.
  • the control unit 8 controls the laser irradiation unit 3 so that the modified regions 12 having different formation depths are formed between the plurality of lines.
  • the formation depth of the modified region 12 in the line marked “Z167” is the shallowest, and the modified region 12 gradually moves away from the line marked “Z167” in the Y direction.
  • the formation depth is deep, and the formation depth of the modified region in the line marked "Z178" is the deepest.
  • the modified region 12 of each line is formed by moving the wafer 20 in the X direction with respect to the laser light L output from the laser irradiation unit 3.
  • the movement of the wafer 20 in the X direction has an outward route (outward route) and a return route (return route), and a modified region 12 on the outward route and a modified region 12 on the return route are formed for each line. In the determination process described later, it is determined whether or not the crack has reached the state for each outward route and each return route.
  • each modified region 12 is shown as each modified region 12, but in reality, two modified regions 12a and 12b are formed as described above.
  • the number of focal points may be single focus, two focal points, or more.
  • the control unit 8 determines whether or not the crack 14 extending from the modified region 12 is in the crack reaching state reaching the surface 21a side of the semiconductor substrate 21 based on the image acquired by the imaging unit 4. To judge. As shown in FIG. 14, the control unit 8 controls the image pickup unit 4 to move the focal point F in the Z direction and acquire a plurality of images.
  • the focal point F1 is the focal point where the tip 14e of the crack 14 extending from the modified region 12b to the back surface 21b side is imaged.
  • the focal point F2 is the focal point where the upper end of the modified region 12b is imaged.
  • the focal point F3 is the focal point where the upper end of the modified region 12a is imaged.
  • the focal point F4 is the focal point of the virtual image region in which the tip 14e of the crack 14 extending from the modified region 12a to the surface 21a side is imaged, and is the target point with the position of the tip 14e (virtual focus F4v) with respect to the surface 21a.
  • the focal point F5 is the focal point of the virtual image region in which the lower end of the modified region 12a is imaged, and is a target point with the position of the lower end of the modified region 12a (virtual focus F5v) with respect to the surface 21a.
  • the direction toward the back surface 21b is the positive direction
  • the thickness of the wafer 20 is T
  • the distance from the back surface 21b side of the focal point F1 is A
  • B the distance from the back surface 21b side of the focal point F3 is D
  • the distance from the back surface 21b side of the focal point F4 is G
  • the distance from the back surface 21b side of the focal point F5 H
  • the position c of the lower end of the modified region 12b, the position e of the lower end of the modified region 12a, the position c'of the upper end of the modified region 12b, and the position e'of the upper end of the modified region 12a are the laser machining apparatus 1. It can be specified according to the Z height which is the processing depth (height) in the above and the constant (DZ rate) in consideration of the refractive index of the silicon of the wafer 20.
  • the Z height at the lower end of the modified region 12b is the Z height at the lower end of SD2
  • the Z height at the lower end of the modified region 12a is the Z height at the lower end of SD1
  • the Z height at the upper end of the modified region 12b is the Z height at the upper end of SD2
  • the Z height at the upper end of the modified region 12a is the Z height at the lower end of SD2
  • the position c at the lower end of the modified region 12b T-SD2 lower end Z height ⁇ DZ
  • the position at the lower end of the modified region 12a e T-SD1 lower end Z height ⁇ DZ
  • Upper end position c' T-SD2 upper end Z height x DZ + laser energy of modified region 12b
  • SD layer width expected from modified region 12a upper end position e' T-SD1 upper end Z height x DZ + laser energy This is the SD layer width expected from.
  • the control unit 8 sets an imaging section, an imaging start position, an imaging end position, and an imaging Z interval (interval in the Z direction) according to the type of crack 14 to be detected.
  • the imaging unit 4 continuously performs imaging at a set interval (Z interval of imaging) from the imaging start position to the imaging end position of the set imaging section.
  • the imaging section is, for example, the modified region 12b to the upper crack.
  • the tip 14e is set at a position sufficiently close to the back surface 21b so that it cannot be detected.
  • the light collecting position of the modified region 12b can be obtained from the information at the time of forming the modified region 12b in the forming process.
  • the imaging section may be the entire section in the Z direction that can be imaged, that is, the virtual image region Vi (see FIG. 14) to the back surface 21b of the condensing position of the modified region 12a.
  • the imaging start position is, for example, the position farthest from the back surface 21b in the imaging section.
  • the imaging end position is, for example, a position where the tip 14e of the upper crack is detected, a position where the tip 14e of the upper crack is detected and then not detected at all, or a position where all the imaging of the imaging section is completed.
  • the Z interval (interval in the Z direction) of imaging is variable in the imaging process (for example, immediately after the start of imaging, the imaging is roughly performed with a wide imaging interval, and when the tip 14e of the upper crack is detected, the imaging interval is narrowed and finely captured). It may be constant from the imaging start position to the imaging end position.
  • the imaging section is, for example, the upper end of the modified region 12a. It is set in the virtual image region of the condensing position from the position to the modified region 12b.
  • the upper end position of the modified region 12a can be obtained from the information on the condensing position at the time of forming the modified region 12a in the forming process and the width of the modified region 12a.
  • the virtual image region of the condensing position of the modified region 12b can be obtained from the information at the time of forming the modified region 12b in the forming process.
  • the imaging section may be the entire section in the Z direction that can be imaged, that is, the virtual image region Vi (see FIG. 14) to the back surface 21b of the condensing position of the modified region 12a.
  • the imaging start position may be, for example, the position farthest from the back surface 21b in the imaging section, or may be the position farthest from the back surface 21b in the imaging section.
  • the imaging end position is, for example, a position where the tip 14e of the lower crack is detected, a position where the tip 14e of the lower crack is detected and then not detected at all, or a position where all the imaging of the imaging section is completed.
  • the Z interval (interval in the Z direction) of imaging is variable in the imaging process (for example, immediately after the start of imaging, the imaging is roughly performed with a wide imaging interval, and when the tip 14e of the lower crack is detected, the imaging is finely performed with a narrow imaging interval). It may be constant from the imaging start position to the imaging end position.
  • the detection (determination) process of the tip 14e of the image captured by the imaging unit 4 may be performed every time one image is captured, or is performed after all the images in the imaging section have been captured. You may. Further, the process of cleansing the imaged data and detecting (determining) the tip 14e may be performed by using a technique such as artificial intelligence.
  • FIG. 15 shows an example of the imaging result at each measurement point.
  • the measurement points here are a plurality of lines “Z167" to "Z178" (see FIG. 13) formed in the forming process and having different formation depths of the modified regions 12.
  • the formation depth of the modified region 12 of "Z167" is the shallowest, and the formation depth of the modified region 12 becomes deeper as the value of Z increases, and the modified region 12 of "Z178" The formation depth of is the deepest.
  • the control unit 8 moves the focal point F in the Z direction by controlling the imaging unit 4 for each measurement point (modified region 12 of each line) to acquire a plurality of images, and obtains a plurality of images from the images (that is, from the actually measured values).
  • A the position of the tip 14e of the upper crack
  • b the position of the upper end of the modified region 12b (SD2)
  • d the position of the upper end of the modified region 12a (SD1)
  • f the lower.
  • the position of the crack tip 14e is derived.
  • the control unit 8 has e: the position of the lower end of the modified region 12a, e': the position of the upper end of the modified region 12a, c, as shown in FIG.
  • the ST and BHC information shown at the bottom of the table in FIG. 15 is information acquired by microscopic observation in order to confirm the accuracy of the determination process by the control unit 8 described later.
  • the laser irradiation unit 3 and the imaging unit 4 are provided in the same apparatus, and the formation process of the modified region 12 for inspection and the imaging process of the modified region 12 are continuous.
  • the laser irradiation unit and the imaging unit were separate devices, so that the crack 14 was extended when the wafer 20 was transferred between the devices. It has been closed (the crack 14 has expanded more than the result of imaging by the actual laser processing device 1).
  • the accuracy of the determination process accuracy of the process for identifying the crack arrival state
  • the determination process of the control unit 8 will be described based on the imaging result.
  • FIG. 16 is a graph of the imaging results shown in FIG. 15, where the horizontal axis indicates the measurement point and the vertical axis indicates the position (position when the surface 21a is used as a reference position). Further, as in FIG. 15, in FIG. 16, the information of ST or BHC acquired by microscopic observation is shown at the bottom.
  • the control unit 8 starts from the modification region 12 to the back surface 21b in order from the measurement point (line) where the formation depth of the modification region 12 is shallow, or from the measurement point (line) where the formation depth of the modification region 12 is deep.
  • the position of the tip 14e on the back surface 21b side of the upper crack, which is a crack extending to the side, may be derived, and it may be determined whether or not the crack has reached the state based on the amount of change in the position of the tip 14e.
  • the control unit 8 derives the position of the tip 14e of the upper crack in order from the measurement point where the formation depth of the modification region 12 is shallow and derives the amount of change in the position of the tip 14e, the upper crack
  • a predetermined value for example, 20 ⁇ m
  • the control unit 8 derives the change amount of the upper crack tip 14e.
  • the amount of change in the position of is larger than a predetermined value (for example, 20 ⁇ m)
  • the measurement points are arranged in ascending order of the formation depth of the modified region 12, and a: the change in the position of the tip 14e of the upper crack is observed. It can be seen that the difference) is extremely large compared to the amount of change between other measurement points.
  • Z171 is a measurement point having the deepest formation depth of the modified region 12 among the measurement points to be ST
  • Z172 is a measurement point having the shallowest formation depth of the modified region 12 among the measurement points to be BHC. is there. From this, the positions of a: the tip 14e of the upper crack are derived in order from the measurement point where the formation depth of the modified region 12 is shallow, or from the measurement point where the formation depth of the modified region is deep, and the tip is derived. It can be said that it is possible to derive the amount of change in the position of 14e and determine whether or not the state is BHC (crack arrival state) based on whether or not the amount of change is larger than a predetermined value.
  • the control unit 8 starts from the modification region 12 to the back surface 21b in order from the measurement point (line) where the formation depth of the modification region 12 is shallow, or from the measurement point (line) where the formation depth of the modification region 12 is deep.
  • the difference between the position of the tip 14e on the back surface 21b side of the upper crack, which is a crack extending to the side, and the position where the modified region 12 is formed is derived, and based on the amount of change in the difference, whether or not the crack is reached. May be determined. Specifically, when the control unit 8 derives the above-mentioned difference in order from the measurement point where the formation depth of the modification region 12 is shallow, the amount of change in the difference becomes larger than a predetermined value (for example, 20 ⁇ m).
  • a predetermined value for example, 20 ⁇ m
  • the measurement points are arranged in ascending order of the formation depth of the modified region 12, and ab: the difference between the position of the tip 14e of the upper crack and the position of the upper end of the modified region 12b (hereinafter, If we simply look at the change in "the difference between the position of the tip 14e of the upper crack and the position where the modified region 12b is formed"), the amount of change between Z171 and Z172 is the other. It can be seen that the amount of change between measurement points is extremely large.
  • a the difference between the position of the tip 14e of the upper crack and the position of the lower end of the modified region 12a (hereinafter, simply “the position of the tip 14e of the upper crack and the position where the modified region 12a is formed”.
  • the control unit 8 may determine whether or not it is in the BHC (crack reaching state) based on the presence or absence of the tip 14e on the surface 21a side of the lower crack, which is a crack extending from the modified region 12a to the surface 21a side. .. As shown in FIG. 16, the position of f: the tip 14e of the lower crack is detected at the measurement point of ST, whereas the position of f: the tip 14e of the lower crack is detected at the measurement point of BHC. It has not been. From this, it can be said that it is possible to determine whether or not the condition is BHC (crack arrival state) depending on the presence or absence of the tip 14e of the lower crack.
  • the control unit 8 estimates the length of the crack (specifically, the lower crack) based on the determination result of whether or not it is BHC.
  • the lower end position e the length from the surface 21a to the lower end position e
  • the length L of the lower crack is derived by the following equation (1).
  • the length L of the lower crack can be estimated only from the conditions given in advance without using the measured value.
  • T is the thickness of the wafer 20
  • ZH1 is the Z height corresponding to the lower end of the modified region 12a
  • DZ is the DZ rate.
  • the length L of the lower crack may be derived by the following equation (2) using the conditions given in advance and the actually measured value.
  • D is the length from the back surface 21b to the upper end of the modified region 12a
  • SW is the width of the modified region 12a determined in advance according to the processing conditions.
  • L T- (D + SW) ...
  • the control unit 8 can derive the length L of the lower crack by the following equation (3) based on the actually measured value.
  • D is the length from the back surface 21b to the upper end of the modified region 12a
  • SW is the width of the modified region 12a predetermined according to the processing conditions
  • H is the length from the back surface 21b to the lower end of the modified region 12a.
  • the control unit 8 determines the pass / fail of the inspection based on the estimated length of the lower crack, and when the inspection fails, derives information related to the adjustment of the irradiation conditions of the laser irradiation unit 3 (that is, described above). Perform adjustment processing).
  • the control unit 8 determines whether or not the inspection is successful by comparing, for example, the length of the lower crack with the target value of the crack length.
  • the crack length target value is a target value of the lower crack length and may be a predetermined value. For example, depending on the inspection condition including at least information on the thickness of the wafer 20. It may be a value to be set (details will be described later).
  • the crack length target value may specify the lower limit of the crack length that passes, the upper limit of the crack length that passes, or the crack length that passes. It may specify the range (lower limit and condition) of the width.
  • the control unit 8 defines the lower limit of the crack length at which the crack length target value is acceptable, and when the estimated lower crack length is shorter than the crack length target value, the irradiation condition. It is judged that the inspection fails because the adjustment of is necessary. Further, the control unit 8 inspects when the estimated lower crack length is longer than the crack length target value when the upper limit of the crack length at which the crack length target value passes is specified. Is determined to be unacceptable.
  • control unit 8 defines the range of the crack length at which the crack length target value is acceptable, the estimated lower crack length is outside the range of the crack length target value. Judge that the inspection fails.
  • control unit 8 determines that the inspection is acceptable, the control unit 8 determines that the irradiation conditions are not adjusted (that is, the above-mentioned adjustment process is not performed). However, the control unit 8 may adjust the irradiation conditions according to the user's request even when the inspection is passed.
  • the control unit 8 derives information related to the adjustment of the irradiation conditions of the laser irradiation unit 3 based on the determination result in the determination process. More specifically, the control unit 8 derives information (correction parameter) related to the adjustment of the irradiation condition based on the length of the lower crack estimated according to the determination result. For example, when the length of the lower crack is short (shorter than the crack length target value that defines the lower limit), the control unit 8 sets a correction parameter so that the crack length becomes longer than the crack length target value. Derived.
  • control unit 8 corrects the crack length so that it becomes shorter than the crack length target value, for example, when the lower crack length is long (longer than the crack length target value that defines the upper limit). Derivation of parameters.
  • the information (correction parameter) related to the adjustment of the irradiation condition is, for example, information on the laser and optical set values such as the amount of focused correction, the processing output, and the pulse width.
  • the control unit 8 adjusts the irradiation conditions of the laser irradiation unit 3 based on the derived correction parameters. That is, the control unit 8 sets the derived appropriate values such as the light collection correction amount, the processing output, and the pulse width in the laser irradiation unit 3 so that the crack length becomes longer or shorter than the current state. ..
  • FIG. 17 is a diagram showing an example of a difference in measurement points that becomes BHC when the light collection correction parameter (light collection correction amount) is changed. As shown in the right figure of FIG. 17, in the initial value before the adjustment process, the BHC was set for the first time in Z173, but the focusing correction parameter should be increased by +1 so that the focusing correction amount becomes large.
  • the length of the lower crack can be adjusted to a desired length by adjusting the irradiation conditions of the laser irradiation unit 3 based on the determination result in the determination process.
  • the control unit 8 may derive information related to the adjustment of the irradiation condition and adjust the irradiation condition only when the user requests the adjustment of the irradiation condition in the user request (for details, refer to the details. See below).
  • FIG. 18 is a flowchart of the first inspection method.
  • FIG. 19 is a flowchart of the second inspection method.
  • FIG. 20 is a flowchart of the third inspection method.
  • FIG. 21 is a flowchart of the fourth inspection method.
  • the modified region 12 is formed for all the lines to be inspected, it is determined whether or not the modified region 12 is BHC in order from the line with the shallowest formation depth. , BHC, the irradiation conditions are adjusted (correction parameter adjustment) based on the length of the lower crack.
  • the modified region 12 is formed for all the lines to be inspected (step S1).
  • the modified regions 12 of the outward route and the return route are formed for each of the lines “Z167” to “Z178” shown in FIG.
  • the formation depth of the modified region 12 in the line marked “Z167” is the shallowest, and it is separated from the line marked “Z167” in the Y direction (the value of Z increases).
  • the formation depth of the modified region 12 gradually becomes deeper, and the modified region 12 of each line is formed so that the formation depth of the modified region 12 in the line marked “Z178” becomes the deepest. ..
  • Step S1 will be specifically described.
  • the wafer 20 is prepared and placed on the stage 2 of the laser processing apparatus 1.
  • the wafer 20 to be used may be in a state where a film (tape) is attached or not attached.
  • the size, shape, and type (material, crystal orientation, etc.) of the wafer 20 are not limited.
  • the alignment is performed by moving the stage 2 in the X direction, the Y direction, and the ⁇ direction (rotational direction centered on the axis parallel to the Z direction).
  • the stage 2 moves in the Y direction so that the scheduled machining line of the outbound route of the "Z167" is directly below the laser irradiation unit 3, and the laser irradiation unit 3 moves to the machining depth corresponding to the "Z167".
  • the laser irradiation unit 3 starts irradiating the laser beam L, and the stage 2 moves in the X direction at a predetermined processing speed.
  • the modified regions 12 are formed along the outward line of the “Z167” extending in the X direction.
  • the stage 2 moves in the Y direction so that the scheduled machining line on the return path of the "Z167" is directly below the laser irradiation unit 3, and the laser irradiation unit 3 moves to a machining depth corresponding to the "Z167". .. Then, the laser irradiation unit 3 starts irradiating the laser beam L, and the stage 2 moves in the X direction at a predetermined processing speed.
  • the modified regions 12 two rows of modified regions 12a and 12b
  • Such formation of the modified regions 12a and 12b on the outward route and the return route is performed for all lines (“Z167” to “Z178”) while setting the processing depth to the depth corresponding to each line.
  • step S1 is the process of step S1.
  • the control unit 8 detects the position of the tip 14e of the upper crack on the line having the shallowest formation depth and the second shallowest line of the modified region 12 (step S2). Specifically, first, the stage 2 moves in the X direction and the Y direction so that the outbound line of the “Z167” is directly below the image pickup unit 4, and the image pickup unit 4 moves to the image pickup start position. The imaging unit 4 continuously performs imaging at a set interval (Z interval of imaging) from the imaging start position to the imaging end position. The control unit 8 cleanses a plurality of image data acquired by the image pickup unit 4 and detects the tip 14e of the upper crack.
  • the stage 2 moves in the X direction and the Y direction so that the outbound line of the “Z168” is directly below the image pickup unit 4, and the image pickup unit 4 moves to the image pickup start position.
  • the imaging unit 4 continuously performs imaging at a set interval (Z interval of imaging) from the imaging start position to the imaging end position.
  • the control unit 8 cleanses a plurality of image data acquired by the image pickup unit 4 and detects the tip 14e of the upper crack. The above is the process of step S2.
  • step S3 it is determined whether or not the second shallowest line is BHC (crack arrival state) (step S3).
  • the control unit 8 sets the outbound line of the "Z168” based on the position of the tip 14e of the upper crack in the outbound line of the "Z167" and the position of the tip 14e of the upper crack in the outbound line of the "Z168". It is determined whether or not it is BHC. Specifically, when the amount of change in the position of the tip 14e of the upper crack between the two lines is larger than a predetermined value, the control unit 8 determines that the outbound line of "Z168" is BHC.
  • the control unit 8 derives a difference between the position of the tip 14e of the upper crack and the position where the modified region 12b is formed with respect to the outbound line of "Z167" and the outbound line of "Z168", and changes in the difference.
  • the amount is larger than a predetermined value, it may be determined that the outbound line of "Z168" is BHC.
  • step S4 the position of the tip 14e of the upper crack is detected for the next shallowest line (third shallowest line) (step S4), and the second shallowest line.
  • step S4 Based on the position of the tip 14e of the upper crack and the position of the tip 14e of the upper crack of the third shallowest line, it is determined whether or not the third shallowest line is BHC (crack arrival state) (step). S3).
  • the processes of steps S3 and S4 are repeated while gradually moving to a line having a deeper formation depth until it is determined to be BHC in step S3.
  • the processes of steps S3 and S4 are performed separately on the outward route and the return route. For example, after the BHC line is specified for the outward route, it is similarly determined whether or not the modified region 12 is BHC in order from the line with the shallowest formation depth for the return route, and the BHC line is specified. To.
  • step S3 when a line to be BHC is specified for the round-trip route, the control unit 8 subsequently determines whether or not the length of the lower crack is acceptable for each of the round-trip routes (step S5). Specifically, the control unit 8 derives the length of the lower crack by any of the above equations (1) to (3), and compares the length of the lower crack with the target value of the crack length. , Judge the pass / fail of the inspection.
  • the inspection is not performed when the estimated lower crack length is shorter than the crack length target value. Judge as passing. Further, the control unit 8 inspects when the estimated lower crack length is longer than the crack length target value when the upper limit of the crack length at which the crack length target value passes is specified. Is determined to be unacceptable. Further, when the control unit 8 defines the range of the crack length at which the crack length target value is acceptable, the estimated lower crack length is outside the range of the crack length target value. Judge that the inspection fails.
  • the control unit 8 may derive a Z height to be BHC from the Z height corresponding to the line to be BHC, compare the Z height with the target Z height, and determine the pass / fail of the inspection. In this case, the control unit 8 may determine that the inspection has passed if the derived Z height matches the target Z height, and may determine that the inspection has failed if they do not match. If it is determined in step S5 that the inspection has passed, the inspection ends.
  • the control unit 8 adjusts the irradiation conditions of the laser irradiation unit 3 (correction parameter adjustment). (Step S6). Specifically, the control unit 8 derives information (correction parameter) related to the adjustment of the irradiation condition based on the estimated length of the lower crack. For example, when the length of the lower crack is short (shorter than the crack length target value that defines the lower limit), the control unit 8 sets a correction parameter so that the crack length becomes longer than the crack length target value. Derived.
  • control unit 8 corrects the crack length so that it becomes shorter than the crack length target value, for example, when the lower crack length is long (longer than the crack length target value that defines the upper limit). Derivation of parameters.
  • the information (correction parameter) related to the adjustment of the irradiation condition is, for example, information on the laser and optical set values such as the amount of focused correction, the processing output, and the pulse width. Then, the control unit 8 adjusts the irradiation conditions of the laser irradiation unit 3 by setting the derived appropriate values such as the light collection correction amount, the processing output, and the pulse width in the laser irradiation unit 3.
  • the processes after step S1 are executed again, and it is confirmed whether the length of the lower crack is a desired length.
  • the new modified region 12 is formed in the region of the wafer 20 in which the modified region 12 has not yet been formed.
  • the above is the first inspection method.
  • the BHC determination may be performed based on the presence or absence of the tip 14e of the lower crack. That is, following step S1, the shallowest line is subjected to BHC determination based on the presence or absence of the tip 14e of the lower crack, and gradually moves to a line having a deeper formation depth until it is determined to be BHC, which is BHC. If it is determined that, the process of step S5 may be performed.
  • the position of the tip 14e of the upper crack is detected in order from the line having the shallowest formation depth in step S2, and it is determined in step S3 whether or not it is BHC.
  • the present invention is not limited to this, and in step S2, the position of the tip 14e of the upper crack is detected in order from the line having the deepest formation depth, and in step S3, it may be determined whether or not it is ST. ..
  • the processes of steps S3 and S4 are repeated while gradually moving to a line having a shallow formation depth until it is determined to be ST in step S3.
  • the length of the lower crack may be estimated based on the information of the line finally determined to be BHC, and the processing after step S5 may be performed. ..
  • the second inspection method shown in FIG. 19 it is determined whether or not BHC is formed in order from the line where the formation depth of the modified region 12 is shallow (or deep), and the irradiation conditions are adjusted (correction parameter adjustment). It is the same as the first inspection method in that it is the same as the first inspection method, but the formation process and the determination process are performed line by line instead of performing the formation process for all the lines (however, the formation process is only the first 2). It differs from the first inspection method in that the line is performed). In the following, the differences from the first inspection method will be mainly described, and duplicate description will be omitted.
  • the modified region 12 having the shallowest formation depth is first formed (step S11). That is, the modified region 12 of the outbound line of “Z167” supported by FIG. 13 is formed. Subsequently, the control unit 8 detects the position of the tip 14e of the upper crack on the outbound line of “Z167”, which is the line where the formation depth of the modified region 12 is the shallowest (step S12). Subsequently, the control unit 8 forms the modified region 12 having the second shallowest formation depth (step S13). That is, the modified region 12 of the outbound line of "Z168” is formed. Subsequently, the control unit 8 detects the position of the tip 14e of the upper crack on the outbound line of “Z168”, which is the line on which the modified region 12 was formed immediately before (step S14).
  • step S15 it is determined whether or not the second shallowest line is BHC (crack arrival state) (step S15).
  • the control unit 8 sets the outbound line of the "Z168” based on the position of the tip 14e of the upper crack in the outbound line of the "Z167" and the position of the tip 14e of the upper crack in the outbound line of the "Z168". It is determined whether or not it is BHC. Specifically, when the amount of change in the position of the tip 14e of the upper crack between the two lines is larger than a predetermined value, the control unit 8 determines that the outbound line of "Z168" is BHC.
  • the control unit 8 derives a difference between the position of the tip 14e of the upper crack and the position where the modified region 12b is formed with respect to the outbound line of "Z167" and the outbound line of "Z168", and changes in the difference.
  • the amount is larger than a predetermined value, it may be determined that the outbound line of "Z168" is BHC.
  • step S15 If it is determined in step S15 that it is not BHC, a modified region of the outbound line of "Z169" having the next shallowest formation depth is formed (step S16), and the modified region 12 is formed immediately before.
  • the position of the tip 14e of the upper crack is detected with respect to the outbound line of "Z169" (step S14).
  • step S15 it is determined whether or not the outbound line of "Z169" is in the BHC (crack arrival state) (step S15). In this way, the processes of steps S16, S14, and S15 are repeated while gradually moving to a line having a deeper formation depth until it is determined to be BHC in step S15.
  • the BHC line is also specified for the return line by the processes of steps S11 to S15. Since the processes of steps S17 and S18 are the same as the processes of steps S5 and S6 described above, the description thereof will be omitted.
  • the above is the second inspection method.
  • the BHC determination may be performed based on the presence or absence of the tip 14e of the lower crack. That is, following step S11, the shallowest line is subjected to BHC determination based on the presence or absence of the tip 14e of the lower crack, and gradually moves to a line having a deeper formation depth until it is determined to be BHC, which is BHC. If it is determined that, the process of step S17 may be performed.
  • the modified region 12 is formed at the formation depth expected to be BHC to determine whether or not it is BHC, and if it is not BHC, the lower crack becomes longer.
  • the irradiation conditions are adjusted (correction parameter adjustment).
  • the differences from the first inspection method will be mainly described, and duplicate description will be omitted.
  • the modified region 12 is first formed at the target Z height (Z height expected to be BHC) in order to form the modified region 12 at the formation depth expected to be BHC. (Step S21). Then, it is determined whether or not the line on which the modified region 12 is formed is in the BHC (crack arrival state) (step S22). The control unit 8 determines whether or not the BHC (crack reaching state) is achieved, for example, based on the presence or absence of the tip 14e on the surface 21a side of the lower crack, which is a crack extending from the modified region 12a to the surface 21a side.
  • step S22 determines whether the modified region 12 is BHC even though the modified region 12 is formed at a formation depth expected to be BHC.
  • the control unit 8 determines the irradiation conditions of the laser irradiation unit 3. (Correction parameter adjustment) is performed (step S23). The processes of steps S23, S21, and S22 are repeated until it is determined to be BHC in step S22. If it is determined to be BHC in step S22, the inspection ends. The above is the third inspection method.
  • the lower crack in addition to the processing of the third inspection method, when the length of the lower crack is too long, a reverse correction process for shortening the length of the lower crack is performed.
  • the third inspection method shown in FIG. 20 when the line to be BHC is not BHC and the lower crack is short, the lower crack can be set to a desired length by adjusting the irradiation conditions.
  • the correction parameter is determined to be BHC without being adjusted even once, the length of the lower crack can be confirmed to be sufficiently long, but the length of the lower crack is long. It has not been possible to confirm whether or not the length is excessively long, and if it is excessively long, the length of the lower crack cannot be shortened.
  • the fourth inspection method when it is determined that BHC is obtained without adjusting the correction parameters even once, a modified region is formed at a formation depth that is not expected to be BHC to determine whether or not it is BHC.
  • the irradiation condition is adjusted (reverse correction processing) so that the lower crack is shortened in the case of BHC.
  • Steps S31 to S33 of the fourth inspection method are the same as the processes of steps S21 to S23 of the third inspection method described above.
  • the fourth inspection method when it is determined in step S32 that BHC is formed, it is determined whether or not the parameters have been adjusted (step S34). If the correction parameter of step S33 has been adjusted before the process of step S34 is performed, it is determined that the parameter has been adjusted and the inspection ends. On the other hand, if the correction parameter adjustment in step S33 is not performed before the processing in step S34, the Z height in which the modified region 12 is formed is shallower than the target Z height (for example, "target". The modified region 12 is formed at the Z height of "Z height-1", which is assumed not to be BHC) (step S35).
  • step S35 it is determined in step S35 whether or not the line on which the modified region 12 is formed is in the BHC (crack arrival state) (step S36).
  • the control unit 8 determines whether or not the BHC (crack reaching state) is achieved, for example, based on the presence or absence of the tip 14e on the surface 21a side of the lower crack, which is a crack extending from the modified region 12a to the surface 21a side.
  • step S37 When the modified region 12 is formed at a formation depth that is not expected to be BHC but is determined to be BHC in step S36, the control unit 8 irradiates the laser irradiation unit 3.
  • the condition is adjusted (correction parameter adjustment) (step S37).
  • the correction parameter adjustment in this case is a process for shortening the lower crack that is too long, and is a correction process (reverse correction process) in the direction opposite to the correction parameter adjustment in step S33.
  • the processes of steps S37, S35, and S36 are repeated until it is determined in step S36 that it is not BHC. If it is determined in step S36 that it is not BHC, the inspection ends.
  • the above is the fourth inspection method.
  • the "screen” is a screen displayed to the user when executing the crack length inspection and adjustment process, prompting the user to perform a setting operation for inspection, and displaying the inspection and adjustment results.
  • This is a GUI (Graphical User Interface) screen.
  • the 22 and 23 show inspection condition setting screens.
  • the setting screen is displayed on the display 150 (input unit, output unit).
  • the display 150 has a function as an input unit for receiving an input from a user and a function as an output unit for displaying a screen to the user.
  • the display 150 accepts an input of inspection conditions including at least information on the thickness of the wafer, and outputs a pass / fail inspection based on the determination result.
  • the display 150 outputs inquiry information asking whether or not to adjust the irradiation conditions when the inspection fails, and accepts the input of the user request which is the request of the user who responded to the inquiry information.
  • the display 150 may be a touch panel display that receives input from the user by directly touching the user's finger, or may be a display that receives input from the user via a pointing device such as a mouse.
  • machining inspection condition As shown in FIG. 22, on the setting screen of the display 150, “machining inspection condition”, “wafer thickness”, “target ZH”, “target lower end crack length”, “BHC inspection / adjustment flow”, “BHC”.
  • Each item of "judgment method” and “pass / fail judgment method” is displayed.
  • a plurality of patterns are prepared for each of the processing inspection conditions, the wafer thickness, the BHC inspection / adjustment flow, the BHC determination method, and the pass / fail determination method, and the user can select one from the drop-down list.
  • the processing inspection conditions are, for example, wafer thickness (t775 ⁇ m, etc.), number of focal points (number of SD layers, 2 focal points, etc.), inspection type (BHC inspection, etc.), and the like.
  • a plurality of patterns are prepared by combining conditions such as wafer thickness, number of focal points, and inspection type. It should be noted that the plurality of patterns of processing inspection conditions may include those in which various conditions can be arbitrarily set by the user. When such machining inspection conditions are selected, for example, the number of focal points, the number of passes, the machining speed, the pulse width, the frequency, the ZH, the machining output, the target lower end crack length, and the like, as shown in FIG.
  • the user can arbitrarily set the standard (allowable range of the target lower end crack length), the target ZH, and the standard (allowable range of the target ZH).
  • normal machining inspection conditions machining inspection conditions in which the user does not arbitrarily set detailed conditions
  • detailed SD machining conditions such as the number of Passes are automatically set according to the machining inspection conditions.
  • the target ZH and the target lower end crack length are automatically displayed (set) when at least one of the processing inspection conditions and the wafer thickness is input.
  • the target ZH is the Z height at which the inspection is judged to pass.
  • the target lower end crack length is the length of the lower crack that is judged to pass the inspection. Allowable ranges (standards) are set for the target ZH and the target lower end crack length, respectively.
  • the BHC inspection / adjustment flow is information indicating which inspection method is used to perform the crack length inspection and adjustment processing, and is, for example, one of the above-mentioned first inspection method to fourth inspection method.
  • the BHC determination method is information indicating which determination method is used to determine whether or not the BHC is BHC. For example, the determination is based on the amount of change in the position of the tip of the upper crack, the position of the tip of the upper crack and the modified region. It is either a judgment based on the amount of change in the difference from the position where the is formed, or a judgment based on the presence or absence of the tip of the lower crack.
  • the pass / fail determination method is information indicating by what determines the pass / fail of the inspection, and is, for example, either both ZH and the lower end crack length, only ZH, or only the lower end crack length.
  • condition 1 wafer thickness (t775 ⁇ m), number of focal points (two focal points), and inspection type (BHC inspection) are selected as processing inspection conditions, and the first inspection method, BHC, is used as the BHC inspection / adjustment flow.
  • the information according to the setting on the setting screen is shown in the upper left
  • the pass / fail result is shown in the upper right
  • the upper crack (SD2 crack) of the shallowest BHC line is shown in the lower left.
  • BHC margin inspection results a list of inspection results (BHC margin inspection results) is shown in the lower right.
  • the back surface state (ST or BHC) in each ZH, the position of the tip of the upper crack (SD2 upper end crack position), the amount of change in the position of the tip of the upper crack, and the length of the lower end crack ( SD1 lower end position) is shown.
  • the line of "Z172" in which the amount of change in the position of the tip of the upper crack changes significantly (changes by 38 ⁇ m) is determined to be the shallowest BHC. It is derived that the lower end crack length is 70 ⁇ m.
  • the line of "Z173" in which the amount of change in the position of the tip of the upper crack changes significantly (changes by 38 ⁇ m) is determined to be the shallowest BHC, and the lower end crack length is 66 ⁇ m. It has been derived.
  • both the outbound and inbound routes are passed in terms of the lower end crack length.
  • the target ZH is ZH173 (Z height of the "Z173" line) ⁇ Z1 (one Z height)
  • both the outward and return routes are also passed in terms of ZH as shown in the pass / fail result.
  • a drop-down list for setting the necessity of adjusting the correction parameter is provided under the information according to the setting on the setting screen, and the user may request the correction parameter adjustment from the drop-down list.
  • FIG. 25 shows an example of a fail screen when the same processing inspection conditions, BHC inspection / adjustment flow, BHC determination method, and pass / fail determination method as in FIG. 24 are selected.
  • the inspection shown in FIG. 25 differs from the inspection shown in FIG. 24 in that the wafer thickness is 771 ⁇ m and the target ZH is ZH172.
  • the line of "Z174" in which the amount of change in the position of the tip of the upper crack is significantly changed is determined to be the shallowest BHC. It is derived that the lower end crack length is 58 ⁇ m.
  • the line of "Z174" where the amount of change in the position of the tip of the upper crack changes significantly (changes by 40 ⁇ m) is determined to be the shallowest BHC, and the lower end crack length is 58 ⁇ m. It has been derived.
  • the target lower end crack length is 65 ⁇ m ⁇ 5 ⁇ m, as shown in the pass / fail result, both the outbound and inbound routes are rejected in terms of the lower end crack length.
  • the target ZH is ZH172 (Z height of the line of "Z172”) ⁇ Z1 (one Z height)
  • both the outward and return routes are rejected in terms of ZH as shown in the pass / fail result.
  • inquiry information asking whether to adjust the correction parameters (adjustment of irradiation conditions) is displayed at the lower end of the fail screen of the display 150, and the display 150 displays the inquiry information. , Accepts the input of the user request in response to the inquiry information. Then, when the user requests that the user adjusts the irradiation condition in the user request, the control unit 8 derives the information related to the adjustment of the irradiation condition and adjusts the irradiation condition.
  • condition 1 wafer thickness (t775 ⁇ m), number of focal points (two focal points), and inspection type (BHC inspection) are selected as processing inspection conditions, and a second inspection method, BHC, is selected as a BHC inspection / adjustment flow.
  • the line of "Z172" in which the amount of change in the difference between the position of the tip of the upper crack and the position where the modified region is formed changes significantly (42 ⁇ m change).
  • the shallowest BHC is the line of "Z173" in which the amount of change in the difference between the position of the tip of the upper crack and the position where the modified region is formed changes significantly (changes by 42 ⁇ m). It has been determined that the lower end crack length is 66 ⁇ m. Now, since the target lower end crack length is 65 ⁇ m ⁇ 5 ⁇ m, as shown in the pass / fail result, both the outbound and inbound routes are passed in terms of the lower end crack length. Further, since the target ZH is ZH173 (Z height of the "Z173" line) ⁇ Z1 (one Z height), both the outward and return routes are also passed in terms of ZH as shown in the pass / fail result.
  • FIG. 27 shows an example of a fail screen when the same processing inspection conditions, BHC inspection / adjustment flow, BHC determination method, and pass / fail determination method as in FIG. 26 are selected.
  • the inspection shown in FIG. 27 differs from the inspection shown in FIG. 26 in that the wafer thickness is 771 ⁇ m and the target ZH is ZH172.
  • the line of "Z173" in which the amount of change in the difference between the position of the tip of the upper crack and the position where the modified region is formed changes significantly (44 ⁇ m change). Is determined to be the shallowest BHC, and the lower end crack length is derived to be 62 ⁇ m.
  • the shallowest BHC is the line of "Z174" in which the amount of change in the difference between the position of the tip of the upper crack and the position where the modified region is formed changes significantly (changes by 44 ⁇ m). It has been determined that the lower end crack length is 58 ⁇ m. Since the target lower end crack length is 65 ⁇ m ⁇ 5 ⁇ m, the return route does not satisfy the conditions as shown in the pass / fail result, and the lower end crack length is rejected. Also, since the target ZH is ZH172 (Z height of the "Z172" line) ⁇ Z1 (one Z height), the return route does not meet the conditions as shown in the pass / fail result, and the ZH point is also rejected. It has become. When the inspection result is unacceptable, inquiry information inquiring whether to adjust the correction parameter (adjustment of the irradiation condition) is displayed at the lower end of the unacceptable screen of the display 150.
  • condition 1 wafer thickness (t775 ⁇ m), number of focal points (two focal points), and inspection type (BHC inspection) are selected as processing inspection conditions, and a third inspection method, BHC, is used as the BHC inspection / adjustment flow.
  • the back surface state (ST or BHC) and the presence or absence of the lower crack tip in each ZH are shown for each outbound and inbound route.
  • the line of "Z172" where the tip of the lower crack is no longer detected is determined to be the shallowest BHC, and the lower crack length is 70 ⁇ m according to ZH. Is derived.
  • the line of "Z173" in which the tip of the lower crack is no longer detected is determined to be the shallowest BHC, and the lower crack length is derived to be 66 ⁇ m according to ZH.
  • the target lower end crack length is 65 ⁇ m ⁇ 5 ⁇ m, as shown in the pass / fail result, both the outbound and inbound routes are passed in terms of the lower end crack length.
  • the target ZH is ZH173 (Z height of the "Z173" line) ⁇ Z1 (one Z height)
  • both the outward and return routes are also passed in terms of ZH as shown in the pass / fail result.
  • FIG. 29 shows an example of a fail screen when the same processing inspection conditions, BHC inspection / adjustment flow, BHC determination method, and pass / fail determination method as in FIG. 28 are selected.
  • the inspection shown in FIG. 29 differs from the inspection shown in FIG. 28 in that the wafer thickness is 771 ⁇ m and the target ZH is ZH172.
  • the line of "Z173" where the tip of the lower crack is no longer detected is determined to be the shallowest BHC, and the lower crack length is 62 ⁇ m according to ZH. Is derived.
  • the line of "Z174" where the tip of the lower crack is no longer detected is determined to be the shallowest BHC, and the lower crack length is derived to be 58 ⁇ m according to ZH. Since the target lower end crack length is 65 ⁇ m ⁇ 5 ⁇ m, the return route does not satisfy the conditions as shown in the pass / fail result, and the lower end crack length is rejected. Also, since the target ZH is ZH172 (Z height of the "Z172" line) ⁇ Z1 (one Z height), the return route does not meet the conditions as shown in the pass / fail result, and the ZH point is also rejected. It has become. When the inspection result is unacceptable, inquiry information inquiring whether to adjust the correction parameter (adjustment of the irradiation condition) is displayed at the lower end of the unacceptable screen of the display 150.
  • the laser processing apparatus 1 of the present embodiment has a stage 2 that supports a wafer 20 having a semiconductor substrate 21 having a front surface 21a and a back surface 21b, a functional element layer 22 formed on the front surface 21a, and a back surface of the semiconductor substrate 21.
  • the laser irradiation unit 3 that irradiates the wafer 20 with laser light from the 21b side, the imaging unit 4 that outputs light having transparency to the semiconductor substrate 21 and detects the light propagating through the semiconductor substrate 21, and the wafer 20. Controlling the laser irradiation unit 3 so that one or more modified regions 12 are formed inside the semiconductor substrate 21 by being irradiated with the laser light, and a signal output from the image pickup unit 4 that has detected the light.
  • the position of the tip on the back surface 21b side of the upper crack which is the crack 14 extending from the modified region 12 to the back surface 21b side of the semiconductor substrate 21, is derived, and based on the position of the tip on the back surface 21b side of the upper crack, A control unit 8 configured to determine whether or not the crack 14 extending from the modified region 12 is in the crack reaching state reaching the surface 21a side of the semiconductor substrate 21 and to execute the crack 14 is provided.
  • the control unit 8 controls the laser irradiation unit 3 so that a modified region 12 having a different formation depth from the other lines included in the plurality of lines is formed along each of the plurality of lines in the wafer 20.
  • the position of the tip on the back surface 21b side of the upper crack and the modified region 12 were formed in order from the line where the formation depth of the modified region 12 was shallow, or from the line where the formation depth of the modified region 12 was deep.
  • a difference from the position is derived, and it is determined whether or not the crack has reached a state based on the amount of change in the difference.
  • the wafer 20 is irradiated with laser light so that the modified region 12 is formed inside the semiconductor substrate 21, and the transmissive light propagating through the semiconductor substrate 21 is imaged, and the imaging result (imaging).
  • the position of the tip of the upper crack on the back surface 21b side which is the crack 14 extending from the modification region 12 toward the back surface 21b side of the semiconductor substrate 21, is derived.
  • the modification regions 12 of the plurality of lines have different formation depths, and the modification regions 12 are formed in order from the shallowest line or the modification region 12.
  • the difference between the position of the tip of the upper crack and the position where the modified region 12 is formed is derived in order from the line with the deepest formation depth, and it is determined whether or not the crack has reached the state based on the amount of change in the difference. Will be done.
  • the above-mentioned difference is derived in order from the line (or deep line) where the formation depth of the modified region 12 is shallow, the crack arrival state and the crack 14 do not reach the surface 21a side of the semiconductor substrate 21.
  • the amount of change in the above-mentioned difference (the amount of change from the line from which the difference was derived immediately before) is larger than that between other lines. From such a viewpoint, in the laser processing apparatus 1, it is determined whether or not the crack has reached a state based on the amount of change in the difference described above. From this, according to the laser processing apparatus 1, it is appropriately confirmed whether or not the crack has reached, that is, whether or not the crack over the modified region 12 is sufficiently extended to the surface 21a side of the semiconductor substrate 21. can do.
  • the laser processing apparatus 1 of the present embodiment has a stage 2 that supports a wafer 20 having a semiconductor substrate 21 having a front surface 21a and a back surface 21b, a functional element layer 22 formed on the front surface 21a, and a back surface of the semiconductor substrate 21.
  • the laser irradiation unit 3 that irradiates the wafer 20 with laser light from the 21b side, the imaging unit 4 that outputs light having transparency to the semiconductor substrate 21 and detects the light propagating through the semiconductor substrate 21, and the wafer 20. Controlling the laser irradiation unit 3 so that one or more modified regions 12 are formed inside the semiconductor substrate 21 by being irradiated with the laser light, and a signal output from the image pickup unit 4 that has detected the light.
  • the position of the tip on the back surface 21b side of the upper crack which is the crack 14 extending from the modified region 12 to the back surface 21b side of the semiconductor substrate 21, is derived, and based on the position of the tip on the back surface 21b side of the upper crack, A control unit 8 configured to determine whether or not the crack 14 extending from the modified region 12 is in the crack reaching state reaching the surface 21a side of the semiconductor substrate 21 and to execute the crack 14 is provided.
  • the control unit 8 controls the laser irradiation unit 3 so that a modified region 12 having a different formation depth from the other lines included in the plurality of lines is formed along each of the plurality of lines in the wafer 20.
  • the position of the tip on the back surface 21b side of the upper crack is derived in order from the line where the formation depth of the modification region 12 is shallow, or from the line where the formation depth of the modification region 12 is deep, and the position of the tip is derived. Based on the amount of change, it is determined whether or not the crack has reached.
  • the wafer 20 is irradiated with laser light so that the modified region 12 is formed inside the semiconductor substrate 21, and the transmissive light propagating through the semiconductor substrate 21 is imaged, and the imaging result (imaging).
  • the position of the tip of the upper crack on the back surface 21b side which is the crack 14 extending from the modification region 12 toward the back surface 21b side of the semiconductor substrate 21, is derived.
  • the modification regions 12 of the plurality of lines have different formation depths, and the modification regions 12 are formed in order from the shallowest line or the modification region 12.
  • the position of the tip of the upper crack is derived in order from the line with the deepest formation depth, and it is determined whether or not the crack has reached the state based on the amount of change in the position of the tip.
  • the crack arrival state and the crack 14 do not reach the surface 21a side of the semiconductor substrate 21.
  • the amount of change in the position of the tip of the upper crack (the amount of change from the line from which the difference was derived immediately before) becomes larger than that between the other lines. From such a viewpoint, in the laser processing apparatus 1, it is determined whether or not the crack has reached the state based on the amount of change in the position of the tip of the upper crack described above. From this, according to the laser processing apparatus 1, it is appropriately confirmed whether or not the crack has reached, that is, whether or not the crack over the modified region 12 is sufficiently extended to the surface 21a side of the semiconductor substrate 21. can do.
  • the control unit 8 determines whether or not the crack has reached the state based on the presence or absence of the tip 14e on the surface 21a side of the lower crack, which is a crack extending from the modified region 12 to the surface 21a side of the semiconductor substrate 21.
  • the presence of the tip 14e on the surface 21a side of the lower crack is confirmed, it is assumed that the crack has not reached the state. Therefore, by determining whether or not the crack has reached the state based on the presence or absence of the tip 14e on the surface 21a side of the lower crack, it is possible to determine with high accuracy whether or not the crack has reached the state.
  • the control unit 8 derives information related to the adjustment of the irradiation conditions of the laser irradiation unit 3 based on the determination result of whether or not the crack has reached. By deriving information related to the adjustment of the irradiation conditions of the laser irradiation unit 3 in consideration of the determination result, for example, when the length of the crack 14 is shorter than the original length, the length of the crack 14 becomes longer. In addition, information for adjusting the irradiation conditions can be derived so that the length of the crack 14 becomes shorter when the length of the crack 14 is longer than the original length. Then, by adjusting the irradiation conditions using the information for adjusting the irradiation conditions derived in this way, the length of the crack 14 can be set to a desired length.
  • the control unit 8 estimates the length of the crack 14 based on the determination result, and derives information related to the adjustment of the irradiation condition based on the estimated length of the crack 14. By deriving the information related to the adjustment of the irradiation conditions based on the estimated length of the crack 14, the adjustment accuracy of the irradiation conditions can be improved, and the length of the crack 14 can be set to the desired length with higher accuracy. it can.
  • the present invention is not limited to the above embodiment.
  • the irradiation conditions are adjusted based on the information related to the adjustment derived by the control unit 8, but the present invention is not limited to this, and the output unit (display 150, etc.) after the control unit 8 derives the information related to the adjustment May output the information related to the adjustment derived by the control unit 8.
  • the irradiation conditions can be adjusted while being manually confirmed by the user, for example, and the length of the crack can be set to a desired length.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Engineering (AREA)
  • Plasma & Fusion (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • General Chemical & Material Sciences (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Manufacturing & Machinery (AREA)
  • Testing Or Measuring Of Semiconductors Or The Like (AREA)
  • Investigating Materials By The Use Of Optical Means Adapted For Particular Applications (AREA)
  • Laser Beam Processing (AREA)
  • Dicing (AREA)

Abstract

La présente invention concerne un dispositif de traitement laser comprenant : une platine qui supporte une tranche ; une unité de projection laser qui projette une lumière laser sur la tranche ; une unité d'imagerie qui détecte la lumière propagée à travers un substrat semi-conducteur ; et une unité de commande qui est configurée de façon à commander l'unité de projection laser de telle sorte qu'une ou plusieurs régions modifiées soient formées à l'intérieur du substrat semi-conducteur en raison de la projection de la lumière laser sur la tranche, et à dériver, sur la base d'un signal émis par l'unité d'imagerie qui a détecté la lumière, une position de pointe d'une fissure supérieure sur le côté arrière du substrat semi-conducteur, ladite fissure s'étendant à partir de la ou des régions modifiées jusqu'au côté arrière et à déterminer, sur la base de la position de pointe de la fissure supérieure sur le côté arrière, si la fissure a été atteinte.
PCT/JP2020/035120 2019-09-18 2020-09-16 Dispositif d'inspection et procédé d'inspection Ceased WO2021054372A1 (fr)

Priority Applications (4)

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KR1020227004588A KR102816180B1 (ko) 2019-09-18 2020-09-16 검사 장치 및 검사 방법
CN202080065240.3A CN114430706B (zh) 2019-09-18 2020-09-16 检查装置及检查方法
DE112020004475.0T DE112020004475T5 (de) 2019-09-18 2020-09-16 Prüfvorrichtung und Prüfverfahren
US17/642,998 US20220331909A1 (en) 2019-09-18 2020-09-16 Inspection device and inspection method

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JP2019169475A JP7305495B2 (ja) 2019-09-18 2019-09-18 検査装置及び検査方法
JP2019-169475 2019-09-18

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DE (1) DE112020004475T5 (fr)
TW (1) TWI868213B (fr)
WO (1) WO2021054372A1 (fr)

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US20220331909A1 (en) 2022-10-20
CN114430706A (zh) 2022-05-03
KR102816180B1 (ko) 2025-06-04
TW202125665A (zh) 2021-07-01
CN114430706B (zh) 2024-10-15
TWI868213B (zh) 2025-01-01
JP2021048236A (ja) 2021-03-25
KR20220062268A (ko) 2022-05-16
JP7305495B2 (ja) 2023-07-10

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